In general, a one-way clutch is equipped with an outer ring and an inner ring rotatable relative to each other, and can transmit a rotational torque in only one direction as a result of engagement of sprags, rollers or the like, which serve to transmit torques between the outer ring and the inner ring, with cam surfaces arranged on a raceway surface of the outer ring or inner ring. The one-way clutch is also constructed to idle whenever a rotational torque is applied in the reverse direction.
Such one-way clutches are known to include a one-way clutch constructed such that rolling elements such as rollers are arranged in pockets (recesses) formed in an inner ring or outer ring and depending on the direction of rotation, the rotation is locked by wedging action produced as a result of engagement of the rolling elements with cam surfaces of the pockets.
In JP-A-2004-251343, for example, lube oil is filled in pockets within which rollers are accommodated, and passages are formed to communicate the adjacent pockets with each other. The lube oil is, therefore, forced to flow out into the adjacent pockets via the passages so that the inner and outer rings and the rollers are positively lubricated at the areas of contact between them.
When a one-way clutch is used at a position to which oil such as engine oil or automatic transmission fluid (ATF) cannot be fed, mere filling of lube oil such as grease in pockets is generally unable to effectively feed the lube oil to slide surfaces, leading to a potential problem that abrasion may take place during high-speed rotation and during idling in high-vibration environments. The arrangement of communicating passages between pockets as in JP-A-2004-251343, therefore, was not always possible to provide a drastic solution. In particular, there is a problem that no sufficient lube oil can be fed to an inner circumferential wall of an outer ring during idling.